Photographic recording tube with a phosphor layer in a thin-window narrow-slit faceplate

ABSTRACT

A faceplate of a thin-window photographic recording tube including a bulb face having provided therein a straight slit extending longitudinally of said bulb face. The faceplate features increased mechanical strength to withstand the atmospheric pressure and improved adhesion to the bulb face. The bonding agent for fastening the faceplate to the bulb face is advantageously isolated from the slit.

United States Patent [72] Inventors Kaoru Tomi Tokyo; Hiroshi Miyama, Tokyo; Tadao Muto, Chofu-shi; Masahiko Kaneko, Tokyo, all of Japan 21 1 Appl. No. 798,408

[22] Filed Feb. 11,1969

[45] Patented Nov. 9, 1971 [73] Assignee Matsushita Electric Industrial Co., Ltd.

Osaka, Japan [32] Priorities Feb. 16, 1968 May 24, 1968, Japan, No. 43/235855; Sept. 7, 1968, Japan, No. 43/70904 [54] PHOTOGRAPHIC RECORDING TUBE WITH A PHOSPHOR LAYER IN A THIN-WINDOW NARROW-SLIT FACEPLATE 2 Claims, 10 Drawing Figs.

[52] US. Cl. 313/92 R, 346/110 [51] Int. Cl Gold 9/42, H0 1 j 29/24 [50] Field of Search 313/74, 92; 346/ 1 i0 [56] References Cited UNITED STATES PATENTS 1,943,109 1/1934 Coolidge 313/74 X Primary Examiner--Roy Lake Assistant Examiner-V. Lafranchi Attorney-Stevens, Davis, Miller & Mosher ABSTRACT: A faceplate of a thin-window photographic recording tube including a bulb face having provided therein a straight slit extending longitudinally of said bulb face. The faceplate features increased mechanical strength to withstand the atmospheric pressure and improved adhesion to the bulb face. The bonding agent for fastening the faceplate to the bulb face is advantageously isolated from the slit.

PATENTEUNUV 9 |97l RIOR ART SHEET 2 [IF 2 Ill/III!) L1 PHOTOGRAPIIIC RECORDING TUBE WITH A PIIOSPIIOR LAYER IN A THIN-WINDOW NARROW-SLIT FACEPLA'IE The present invention relates generally to improvements in a thin-window recording tube and has its particular reference to improvements in the construction of the envelope faceplate of a recording tube of the known slit type.

The construction of the conventional thin-window recording tube is such that an envelope faceplate composed of a sheet of glass or mica coated on one side thereof with a fluorescent material and a thin aluminized backing mounted securely on said side of the glass or mica sheet is adhered to the face of the bulb by means of a suitable bonding agent whereby the slit which is scored in the bulb face is wholly covered by the faceplate. For the purpose of minimizing the loss of output brightness and restricting the diffusion of the beams of light, as is well known, it is important to reduce the overall thickness of the faceplate to a minimum when using the recording tube having such a construction. However, the reduction in the thickness of the faceplate is reflected by lessened mechanical strength of the faceplate, sometimes causing a serious damage thereto due to the atmospheric pressure.

In order to render the faceplate tough enough to withstand the atmospheric pressure, it is proposed to lessen the width of the slit so that the area of the faceplate that is exposed to the vacuum is made significantly smaller. This, in turn, is offset by degraded straightness of the slit, according to the experiments conducted so far.

The invention, therefore, contemplates provision of an improved faceplate of the thin-window recording tube, which faceplate is afforded with sufficient mechanical strength without impairing the straightness thereof.

Reduction in the width of the slit in the bulb face of the recording tube of the type under consideration involves another problem in that, when in mounting the faceplate on the bulb face with use of a bonding agent, the hot fused bonding agent sometimes fails to flow to the boundary of the slit with the resultant decrease in the adhesive power or, what is worse, the agent tends to flow into the slit which consequently becomes clogged with the agent.

Thus, the invention further contemplates provision of improved faceplates of a thin-window recording tube wherein the bonding agent is permitted to cover desired areas of both the bulb face and faceplate.

In the drawings:

FIG. I is a top plan view of the bulb face of a conventional thin-window recording tube;

FIG. 2 is the section on line I-I of FIG. 1;

FIGS. J-A and -B are views showing, in vertical section taken respectively, in the directions along and transverse to the slit, an example of a bulb face with a conventional faceplate;

FIGS. 4-A and -B are views showing, in vertical section taken, respectively, in the directions along and transverse to the slit, an embodiment of the invention;

FIG. 5 is a view showing, in vertical section taken in the direction along the slit, another example of a bulb face with a different form of conventional faceplate;

FIG. 6-A is a view showing, in vertical section taken in the direction transverse to the slit, a second embodiment of the invention;

FIG. 6-B is the cross section taken on line II--II of FIG. 6-A; and

FIG. 7 is a view illustrating a method of mounting the faceplate on the bulb face in a simplified manner.

In the conventional thin-window recording tube, as best illustrated in FIGS. I and 2, a straight slit 1 is scored in the face 2 of the bulb 3. To the bulb face 2 is attached a faceplate 4 by means of the adhesive layer 5 of a suitable bonding agent 5, as seen from FIGS. BA and -B. The faceplate 4 comprises a microsheet 6 of glass or mica, a fluorescent layer 7 of phosphors attached to the inner surface of the sheet 6, and an aluminized backing 8 attached coextensively to the fluorescent layer 7, the areas of said layer 7 and backing 8 being substantially smaller than that of the opening of the slit 1. The slit 1 is thus sealed off by the faceplate 4 by the aid of the adhesive layer 5 of a bonding agent.

The faceplate 4 thus constructed, the portion of the faceplate exposed to the vacuum in the bulb 3 is pulled inwardly so that the faceplate 4 in its entirety is liable to warpage which sometimes leads to damage of the faceplate 4. If the slit 1 is to be narrowed to avoid such a damage, a considerable decrease in the working area of luminescence will result.

With a view to overcoming these difficulties that are inherent in the faceplates of known type, there is provided an improved construction arrangement of the faceplate for thinwindow recording tube, according to the invention.

Turning now to FIGS. 4-A and -B, the microsheet 10 of glass or mica which corresponds with the sheet 6 in the described faceplate 4 of conventional type is made thicker than the conventional ones with the exception of the portion 11 of the sheet 10 facing the interior of the bulb 3. The fluorescent layer 7 of phosphors and the aluminized backing 8 attached to the layer 7 is secured to the portion 11 of the sheet 10 in a manner similar to the faceplate 4 of known type. The area'of the portion 11 may be substantially coextensive with that of the opening of the slit 1.

It will be appreciated that the microsheet I0 can be made sufl'lciently thick with the exception of the thinned portion II so that the mechanical strength of the faceplate as a whole, is greatly increased without lessening the width of the slit I.

For adding'to the mechanical strength of the faceplate, it is advantageous to have the width of the slit reduced to a reasonable extent, as is well known. An example of such construction arrangements of the faceplate of a recording tube of conventional thin-window type is illustrated in FIG. 5. As shown, the bulb 3 has provided in its face 2 of the bulb 3 a faceplate 13 which consists of a sheet 14 of glass secured to the bulb face 2 by means of an adhesive layer 15 of a suitable bonding agent, a microsheet 16 secured to the glass sheet 14 by means of an adhesive layer 17 of a bonding agent similar to the adhesive layer 15, a fluorescent layer 7 of phosphors attached to the inner surface of the microsheet I6, and an aluminized backing 8 attached to the inner surface of the fluorescent layer 7, said layer 7 and backing 8 being substantially coextensive with the area of the opening of the slit I2. Designated at 19 is a conducting layer attached to the inner surface of the envelope of the bulb 3 and held in contact with the aluminized backing 8.

A problem is encountered in such a construction arrangement of the conventional faceplate in that, when in adhering the faceplate I3 to the bulb face 2 with use of a bonding agent at a high temperature, the phosphors constituting the fluorescent layer 8 are subjected to contamination with the hot fused bonding agent by a capillary action and, what is worse, the agent tends to flow into the slit I2 which consequently becomes clogged with the bonding agent. Another problem is that the conducting layer 19 happens to be released or relocated from the aluminized backing 8 to the serious detriment of the contact between both of them when in mounting the faceplate on the bulb face. Adhering the microsheet 16 to the bulb face 2 prior to the application of the fluorescent layer and aluminized backing to the microsheet for the purpose of avoiding such problems can not be practiced for all technical reasons. If, on the other hand, a projection is to be provided on the glass sheet at its entire upper edge for isolating the bonding agent from the interior of the slit, as seen from FIG. 5, it will become extremely difficult to assure sufficient straightness and regular width of the slit 12.

In order to overcome these difficulties, the invention proposes provision of a metal reinforcement at the entire edge of the slit 12.

As illustrated in FIGS. 6-A and -B, there is provided at the entire edge of the slit 12 in the bulb face a metal reinforcement 20 by which are connected the conducting layer 19 and aluminized backing 8. The construction arrangement of the faceplate 13 may be substantially similar to the faceplate 13 shown in FIG. 5.

Since, in this instance, the layers 15 and 17 of a bonding agent are definitely isolated from the interior of the slit 12 by means of the reinforcement 20, it never happens that the bonding agent enters the slit 12 in mounting the faceplate on the face of the bulb. The slit 18 which is defined by the edge of the reinforcement being of the order of 0.5 to 0.8 micron, the slit 12 in the bulb face 2 may be broadened significantly to assure improved straightness and regularity of the width of the slit 12.

It may be mentioned that the material of the metal reinforcement 20 should be common in expansivity with the sheet 14 of glass' For the purpose of prohibiting the bonding agent to ingress into the slit [2 in the bulb face and permitting the agent to flow as far as the edge of the slit satisfactorily, the faceplate may be mounted on the bulb face in a more simplified manner with use of specially designed insert when in fastening the faceplate on the face of the bulb.

As illustrated in FIG. 7, the bulb face 2 has provided therein an outwardly narrowing slit 22 with its outermost width reduced to 0.5 to 0.8 micron. Before mounting the faceplate 6 on the bulb face 2 through an adhesive layer 21 of a bonding agent, a wedge-shaped insert 23 is inserted snugly into the slit 22 in the bulb face with its outer edge held in abutting engagement with the inner face of the faceplate 6. it is important in this instance that the surfaces at which the faceplate 6 and the insert 23 contact with each other be superfinished for mirrorlike surfaces to achieve tight abutment between both of them. The insert 23 thus inserted into the slit 22 in the bulb face makes an obstacle to the entrance of the hot fused bonding agent into the slit when in mounting the faceplate 6 on the bulb face 2 while it allows the bonding agent to flow as far as the edges of the slit 22, thus adding to the tightness of the connection between the faceplate 6 and bulb face 2.

The insert 23 is released from the slit 22 upon completion of the mounting of the faceplate on the bulb face.

The insert may be made of any material that is extraneous to the bonding agent but it may preferably be made of carbon or Meehanite cast iron where a slit glass is used as the bonding agent.

What is claimed is:

1. A faceplate of a thin-window recording tube having an envelope with a conducting layer thereon and including a bulb face having provided therein a straight slit extending longitudinally of said bulb face, which faceplate comprises a transparent microsheet which is substantially coextensive with the area of the opening of said slit, a glass sheet having provided therein a straight slit which is narrower than the slit in the bulb and attached to the inner surface of said microsheet and the bulb face with a bonding agent, a metal reinforcement with a slit therein mounted at the entire edge of said slit in the bulb face and connected with the conducting layer of the tube envelope, said slit being smaller than the slit in the bulb face, a fluorescent layer of phosphors attached to the inner surface of said microsheet and an aluminized backing attached to the inner surface of said fluorescent layer, said aluminized backing being isolated by said metal reinforcement from said bonding agent.

2. The faceplate of claim 1, wherein said metal reinforcement is wedge-shaped.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,619,691 Dated November 9, 1971 Inventor-(s) Kaoru TOMII et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as show below:

The first inventor s name should be corrected as follows instead of "Kaoru Tomi" it should read --Kaoru Tomii--.

In the claim for convention priority, Japanese application N 43/70904 was filed --September a, 1968-- instead of "September 7, 1968".

Signed and sealed this 30th day of May 1972.

(SEAL) At best:

EDLIARD LLFLFTCHER ROBERT GOTTSCHALK Attes ting Officer Commissioner of Patents IRM PO-105U (10-59) USCOMM-DC 00376-P69 fi |.|.S GOVERNMENT PRINTING OFFICE f9. O-JlC-S." 

1. A faceplate of a thin-window recording tube having an envelope with a conducting layer thereon and including a bulb face having provided therein a straight slit extending longitudinally of said bulb face, which faceplate comprises a transparent microsheet which is substantially coextensive with the area of the opening of said slit, a glass sheet having provided therEin a straight slit which is narrower than the slit in the bulb and attached to the inner surface of said microsheet and the bulb face with a bonding agent, a metal reinforcement with a slit therein mounted at the entire edge of said slit in the bulb face and connected with the conducting layer of the tube envelope, said slit being smaller than the slit in the bulb face, a fluorescent layer of phosphors attached to the inner surface of said microsheet and an aluminized backing attached to the inner surface of said fluorescent layer, said aluminized backing being isolated by said metal reinforcement from said bonding agent.
 2. The faceplate of claim 1, wherein said metal reinforcement is wedge-shaped. 